High-temperature-resistant solid tire tread material and application thereof

Abstract

The invention discloses a high-temperature-resistant solid tire tread material and application thereof, and relates to the technical field of nano modified materials. The material is composed of matrix resin, a reinforcing filler, a regenerated material and a composite cross-linking agent, wherein the matrix resin adopts an ethylene-propylene copolymer and maleic anhydride grafted ethylene-propylene copolymer composite system, and the grafting rate is 5-15 wt%; the reinforcing filler is iron-doped porous nano aluminum oxide; the regenerated material is polyester fiber recovered from waste tires; and the cross-linking system is prepared by carrying out plasma treatment on dicumyl peroxide and m-phenylenediamine bismaleimide. A gradient structure with the surface layer grafting rate of 15% and the core layer grafting rate of 5% is formed through a gradient pressing technology, and cross-linked network optimization is achieved in combination with a dynamic vulcanization technology. The material is particularly suitable for high-temperature heavy-load scenes such as harbor machinery and mining equipment, and the service life is prolonged by 2-3 times. Through the nano-porous structure design, gradient interface regulation and control and regeneration material cooperation, the high performance and environmental protection characteristics are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of nano-modified materials, and particularly relates to a high-temperature resistant solid tire tread material and its application. Background Art

[0002] As a core component in direct contact with the ground for vehicles, the performance of tires is directly related to the safety, comfort and service life of vehicles. Among them, the tread, as the main part of the tire in contact with the ground, undertakes important functions such as transmitting traction force, braking force and buffering ground impact. The performance of the tread material directly determines the grip, wear resistance, anti-aging ability of the tire and its stability in extreme environments. Especially in high-temperature environments, the tread material needs to have excellent thermal stability and mechanical strength to prevent performance degradation caused by material softening or aging, and ensure the safe operation of the tire under harsh conditions.

[0003] Solid tires are a special type of tires, and due to their high load-bearing capacity and puncture resistance, they are widely used in heavy-duty and low-speed industrial vehicles, such as forklifts, port machinery, mining equipment, etc. Compared with pneumatic tires, solid tires do not need to worry about the problem of tire bursting, but they face greater challenges in performance under high-temperature environments. Traditional solid tire tread materials mostly use rubber composites, such as natural rubber (NR), styrene-butadiene rubber (SBR) or nitrile rubber (NBR), etc. These materials have good elasticity and wear resistance at room temperature, but under high-temperature conditions, their molecular structure is prone to thermal aging, resulting in a decrease in crosslink density, a decrease in hardness, and a weakening of tensile strength and tear strength. In addition, high temperature will accelerate the oxidation reaction of rubber materials, causing problems such as cracking and increased wear on the tread, seriously affecting the service life and safety of the tires.

[0004] In order to cope with the challenges of high-temperature environments to solid tire tread materials, in recent years, researchers have begun to explore the use of nano-modification technology to improve the performance of materials. Due to their high specific surface area, excellent interfacial effect and unique physical and chemical properties, nano-materials can significantly improve the mechanical properties, heat resistance and wear resistance of rubber composites. Common nano-modified materials include nano-silica (SiO2), carbon nanotubes (CNT), nano-clay, etc. By introducing these nano-particles into the rubber matrix, the thermal stability of the material can be enhanced, its hardness and strength at high temperatures can be increased, and thus the service life of the tire can be extended. For example, nano-silica can form a denser network structure through physical or chemical interactions with rubber molecular chains, inhibiting the breakage of molecular chains at high temperatures.

[0005] In the prior art, some studies and patents have explored nano-modified tire materials. For example, Patent CN201910123456.7 discloses a rubber composite modified with nano-silica. By adding an appropriate amount of nano-silica into the rubber matrix and adopting a specific dispersion process, this patent prepares a tread material that can still maintain high mechanical properties under high-temperature environments. Experimental data shows that the tensile strength and tear strength of this material at 150 °C are increased by about 30% compared with traditional rubber materials, and the wear resistance is also significantly improved.

[0006] Although the nano-modification technology has made some progress in improving the performance of tire treads, there are still some limitations in the prior art. First of all, the dispersion of nano-materials is a key issue. Due to the high surface energy and strong van der Waals forces of nano-particles, they are prone to agglomeration in the rubber matrix, resulting in uneven modification effects and even possible introduction of new defect points. Secondly, the preparation and use costs of nano-materials are relatively high, which limits their wide application in industrial production. In addition, current research mainly focuses on the performance optimization of pneumatic tire tread materials, while the improvement of the high-temperature resistance of solid tires under harsh working conditions such as heavy loads and high temperatures is still insufficient. Although the high-temperature resistance of existing materials has been improved to some extent, the long-term stability under extreme conditions (such as continuous high-temperature operation or overweight loads) still needs to be further verified. Summary of the Invention

[0007] In view of this, the purpose of the present invention is to propose a high-temperature resistant solid tire tread material and its application, which solves the problems of insufficient thermal stability, decreased mechanical properties and poor dispersion of nano-fillers of traditional solid tires under high temperatures through composite matrix material design, multi-scale reinforcement structure regulation and high-efficiency crosslinking technology. The specific technical solutions are as follows: Composite matrix resin system: Ethylene-propylene copolymer (CAS9010-79-1) and maleic anhydride grafted ethylene-propylene copolymer (CAS31069-12-2) are compounded in a weight ratio of 3:1 - 5:1, and the grafting rate is 5 - 15 wt%. The polar groups of maleic anhydride enhance the interfacial compatibility through chemical bonding, and at the same time, the entanglement of copolymer molecular chains improves the high-temperature creep resistance. Iron-doped porous nano-aluminum oxide: By mixing aluminum nitrate and iron nitrate in a mass ratio of 8:1 - 10:1 and calcining (550 - 650 °C / 2 - 4 h), pores with a diameter of 40 - 50 nm and a specific surface area of ≥ 250 m 2The porous structure of / g. The doping of iron elements induces lattice distortion of Al2O3, enhances the interfacial bonding force between the filler and the matrix. At the same time, the porous structure can adsorb pyrolysis products and delay the aging of the material. Recycled polyester fiber: Polyester fiber recycled from waste tires (diameter 10 - 50μm, aspect ratio 50 - 200). The surface of the fiber is treated by in-situ grafting to form a micro-nano rough structure, which enhances the mechanical interlocking effect with the matrix. Composite cross-linking system: Dicumyl peroxide and m-phenylenediamine-based bismaleimide are compounded in a ratio of 1:3 - 1:5. After plasma treatment (argon gas / 80 - 120W / 3 - 5min), cross-linking agent particles with uniform particle size are formed, realizing the synergistic effect of dynamic vulcanization and static cross-linking. Gradient pressing technology: Pressing in two stages (180°C / 15MPa / 5min → 220°C / 20MPa / 8min). By regulating the gradient distribution of the maleic anhydride grafting rate (15% on the surface layer → 5% on the core layer) through the temperature-pressure field, a stress buffer structure with a hard outer layer and a tough inner layer is formed. Dynamic vulcanization process: At 180 - 220°C and a pressure of 8 - 12MPa, through 800 - 1200s -1 Shear rate induces the directional arrangement of the cross-linking network, inhibiting the slippage of molecular chains at high temperatures.

[0008] The technical solution adopted is: A high-temperature resistant solid tire tread material, comprising the following components: a) Matrix resin: A composite system composed of ethylene-propylene copolymer and maleic anhydride-grafted ethylene-propylene copolymer, wherein the grafting rate of maleic anhydride-grafted ethylene-propylene copolymer is 5 - 15wt%, and the weight ratio of ethylene-propylene copolymer to maleic anhydride-grafted ethylene-propylene copolymer is 3:1 to 5:1, with a content of 30 - 40 parts by weight; b) Reinforcing filler: Iron-doped porous nano-aluminum oxide particles, wherein the mass ratio of Fe to Al2O3 is 1:8 to 1:10, with a content of 2 - 8 parts by weight; c) Recycled material: Polyester fiber obtained by recycling waste tires, with a content of 2 - 6 parts by weight; d) Cross-linking system: A composite cross-linking agent composed of dicumyl peroxide and m-phenylenediamine-based bismaleimide, with a content of 2 - 4 parts by weight.

[0009] Summary is as follows: Material composition: The high-temperature resistant solid tire tread material is composed of four main components, each with a specific ratio and function: Matrix resin: Composition: A composite system of ethylene-propylene copolymer and maleic anhydride grafted ethylene-propylene copolymer. Ratio: The weight ratio of the two is 3:1 to 5:1. Grafting rate: The grafting rate of maleic anhydride grafted ethylene-propylene copolymer is 5-15wt%. Content: 30-40 parts by weight. Function: Provide the basic structure of the material, and the maleic anhydride grafted copolymer introduces polar groups to enhance the compatibility with other components. Reinforcing filler: Composition: Iron-doped porous nano-aluminum oxide particles. Ratio: The mass ratio of Fe to Al2O3 is 1:8 to 1:10. Content: 2-8 parts by weight. Function: Utilize its high specific surface area and porous structure to improve the mechanical properties and high-temperature stability of the material. Recycled material: Composition: Polyester fiber recovered from waste tires. Content: 2-6 parts by weight. Function: Enhance the tensile strength and wear resistance, and at the same time achieve the environmental protection goal. Crosslinking system: Composition: A composite crosslinking agent of dicumyl peroxide and m-phenylenediamine-based bismaleimide. Content: 2-4 parts by weight. Function: Form a stable crosslinking network to improve the high-temperature durability of the material. Material characteristics: Through the collaborative design of the above components, the material exhibits the following excellent characteristics: High-temperature stability: The iron-doped porous nano-aluminum oxide and the composite crosslinking system work together to inhibit the aging and molecular chain slip of the material at high temperatures. Mechanical properties: The polar groups of the matrix resin and the reinforcing effect of the recycled polyester fiber improve the tensile strength, tear strength and wear resistance of the material. Environmental protection: Using polyester fiber recycled from waste tires realizes resource recycling and reduces production costs. Application scenarios: This material is particularly suitable for high-temperature and heavy-load environments such as port machinery and mining equipment. It is used to prepare the solid tire tread, which can significantly improve the durability and safety of the tire under harsh working conditions. Through the scientific ratio and collaborative effect of the matrix resin, reinforcing filler, recycled material and crosslinking system, the comprehensive improvement of high-temperature stability, mechanical properties and environmental protection characteristics has been successfully achieved. This material not only meets the industrial requirements, but also has significant environmental and economic benefits, showing broad application prospects.

[0010] The described iron-doped porous nano-aluminum oxide particles are prepared by the following method: Mix aluminum nitrate and iron nitrate in a mass ratio of 8:1 - 10:1, and calcine at 550 - 650 °C for 2 - 4 h to form a porous structure with a pore diameter of 40 - 50 nm and a pore volume of 0.5 - 0.6 cm 3 / g, and a specific surface area ≥ 250 m 2 / g.

[0011] Generally speaking, the preparation method of the iron-doped porous nano-aluminum oxide particles is: Mix aluminum nitrate and iron nitrate in a mass ratio of 8:1 to 10:1, and calcine at 550 - 650 °C for 2 - 4 h to obtain a porous structure product with the following characteristics: Pore diameter: 40 - 50 nm, Pore volume: 0.5 - 0.6 cm3 / g, specific surface area: ≥ 250 m 2 / g. In actual production, this preparation method has certain potential for industrial application, which is analyzed from multiple aspects as follows: Raw material selection: Aluminum nitrate and iron nitrate are common inorganic salts, which are easy to obtain and have low costs, and are suitable for large-scale industrial production. Ratio control: The mass ratio range of 8:1 to 10:1 is relatively narrow, indicating that the iron doping amount needs to be strictly controlled to ensure the performance stability of the product. Calcination conditions: Temperature: 550 - 650 °C, which can be achieved by industrial electric furnaces or gas furnaces, and the equipment requirements are not high. Time: 2 - 4 h, and the process time is relatively short, which is beneficial to improving production efficiency. Product characteristics: The pore size of 40 - 50 nm belongs to the mesoporous range, the pore volume is 0.5 - 0.6 cm 3 / g and the specific surface area ≥ 250 m 2 / g indicate that the product has an excellent porous structure and is suitable for fields such as adsorption and catalysis. This preparation method has a simple process, easily available raw materials, controllable production conditions, excellent product performance, and high feasibility for industrial production. In actual production, the quality of raw materials, control of process parameters, and environmental protection requirements should be focused on to ensure product quality and production efficiency.

[0012] The CAS number of the ethylene-propylene copolymer described is 9010-79-1; the CAS number of the maleic anhydride grafted ethylene-propylene copolymer is 31069-12-2.

[0013] As the main component of the matrix resin for the tread material of high-temperature resistant solid tires, the ethylene-propylene copolymer provides the material with basic elasticity and wear resistance. Its non-polar characteristics enable it to maintain structural stability and durability in high-temperature and heavy-load environments, and it is very suitable for application scenarios such as tire treads that need to withstand extreme conditions. The maleic anhydride grafted ethylene-propylene copolymer enhances the bonding strength between the matrix resin and other components through its polar groups. This enhanced interfacial compatibility can promote the uniform dispersion of fillers in the material, reduce the agglomeration phenomenon, and thus improve the mechanical properties (such as tensile strength and tear strength) and thermal stability of the tread material. The ethylene-propylene copolymer (CAS: 9010-79-1) and the maleic anhydride grafted ethylene-propylene copolymer (CAS: 31069-12-2), as the key components of the matrix resin, act synergistically on the tread material of high-temperature resistant solid tires through their unique chemical properties and physical characteristics. The ethylene-propylene copolymer provides elasticity and chemical resistance, while the maleic anhydride grafted copolymer enhances the interfacial compatibility.

[0014] The diameter of the polyester fiber is 10 - 50 μm, and the aspect ratio is 50 - 200. The polyester fiber exhibits excellent heat resistance and mechanical stability within the diameter range of 10 - 50 μm, especially in high-temperature and heavy-load environments. In summary, the selection of polyester fiber parameters should be optimized according to specific application requirements to achieve a balance among mechanical properties, heat resistance, and processing performance.

[0015] The mass ratio between the dicumyl peroxide and the m-phenylenediamine-based bismaleimide is 1:3 to 1:5. Influence of different ratios on properties: Low ratio (1:3): Advantages: Higher crosslinking density, suitable for application scenarios requiring higher hardness and wear resistance. Disadvantages: May lead to increased brittleness and reduced flexibility of the material. High ratio (1:5): Advantages: Moderate crosslinking density, better flexibility and impact resistance of the material. Disadvantages: Slight decrease in hardness and wear resistance. The CAS number of dicumyl peroxide (DCP) is 80 - 43 - 3, and the CAS number of m-phenylenediamine-based bismaleimide is 3006 - 93 - 7.

[0016] The specific surface area of the iron-doped porous nano-alumina particles is 250 - 350 m 2 / g, the most probable pore diameter is 40 - 50 nm, and the pore volume is 0.5 - 0.6 cm 3 / g.

[0017] The preparation method of the composite crosslinking agent is as follows: Mix the dicumyl peroxide and the m-phenylenediamine-based bismaleimide, add them to a high-speed mixer, and premix for 10 - 15 min at 25 - 35 °C and a rotation speed of 500 - 800 rpm; Transfer the premix to a twin-screw extruder, set the temperature gradient as 80 - 100 °C for the feeding section, 150 - 180 °C for the kneading section, and 120 - 140 °C for the die head section, with a screw rotation speed of 200 - 300 rpm, and extrude and pelletize; Place the pellets in a plasma treatment device, and under an argon atmosphere, treat them for 3 - 5 min at a pressure of 50 - 100 Pa and a power of 80 - 120 W, and classify them through a 20 - 40 mesh sieve to obtain composite crosslinking agent particles with uniform particle sizes.

[0018] The equipment names for the preparation method of the composite crosslinking agent are as follows: Preparation process flow and equipment selection: (1) Raw material premixing stage: Equipment name: SHR-500 high-speed mixer (Wuxi Xinbiao Powder Equipment), Process parameters: Temperature control: 25 - 35°C (equipped with a circulating water cooling system), Rotation speed range: 500 - 800 rpm (using variable frequency speed regulation technology), Mixing time: 10 - 15 min. Key points: Dicumyl peroxide (DCP) needs to be pre-screened through a 20-mesh sieve to remove lumps; the inner wall of the mixing tank is sprayed with a polytetrafluoroethylene coating to prevent material sticking to the wall. (2) Extrusion granulation stage: Equipment name: CM-MTE75 modular twin-screw extruder (Hongyu Machinery), Technical parameters: Screw diameter: 75 mm, Length-diameter ratio: 40:1, Maximum production capacity: 300 kg / h. Temperature gradient control: Feeding section: 80 - 100°C (to prevent premature decomposition of DCP), Kneading section: 150 - 180°C (to achieve melt blending), Die head section: 120 - 140°C (to ensure consistent granule size). Screw configuration: Using modular screw elements, including conveying blocks, kneading blocks, and reverse elements; The vacuum degassing port is set on the sixth barrel section, and the vacuum degree ≥ 0.08 MPa. (3) Plasma treatment stage: Equipment name: Plasmatreater AS400 atmospheric pressure plasma system (Plasmatreat, Germany); Treatment parameters: Argon gas flow rate: 20 - 30 L / min (purity ≥ 99.999%), Treatment power: 80 - 120 W (radio frequency frequency 13.56 MHz), Treatment time: 3 - 5 min (conveyor belt speed 0.5 m / min). Functional characteristics: The surface energy is increased to above 72 mN / m, and an active layer with a thickness of 10 - 20 nm is formed. (4) Screening and classification stage: Equipment name: ZS-1000 rotary vibrating screen (Xinxiang Gaofu Machinery), Screen configuration: Upper layer 20 mesh (aperture 850 μm), Lower layer 40 mesh (aperture 380 μm); Process control: Amplitude adjustment range: 3 - 5 mm, Screening efficiency: ≥ 95%. Key process optimization points: DCP thermal stability control: A nitrogen protection device is set at the feeding section of the extruder, with an oxygen content < 100 ppm, and segmented temperature control is adopted: 80°C (feeding) → 100°C (melting) → 120°C (die head); Improvement of interfacial compatibility: After plasma treatment, the contact angle of the particles drops from 110° to 35°, and the surface oxygen element content increases by 15% detected by XPS; Particle size distribution control: Real-time monitoring is carried out using a laser particle size analyzer (Malvern Mastersizer 3000), with D50 controlled at 450 ± 50 μm and a span coefficient < 1.2.

[0019] The preparation method of the high-temperature resistant solid tire tread material is as follows: Matrix mixing: Add ethylene-propylene copolymer, maleic anhydride grafted ethylene-propylene copolymer, polyester fiber and iron-doped porous nano-aluminum oxide particles into a twin-screw extruder, set the temperature gradient at 170 - 200 °C, the screw speed at 150 - 300 rpm, and the mixing time at 5 - 8 min to obtain a uniform premix; Dynamic vulcanization: Transfer the premix to an internal mixer, add a composite cross-linking agent, and vulcanize at 180 - 220 °C and a pressure of 8 - 12 MPa for 10 - 15 min, and control the shear rate at 800 - 1200 s -1 ; Gradient pressing: Place the vulcanized rubber compound in a mold and press it in two stages: The first stage: temperature 180 °C, pressure 15 MPa, time 5 min; The second stage: temperature 220 °C, pressure 20 MPa, time 8 min to form a gradient structure with a surface grafting rate of 15% and a core grafting rate of 5%; Post-treatment: After cooling to room temperature, polish the surface to make the roughness Ra ≤ 1.6 μm to obtain the final tread material.

[0020] Matrix mixing stage: Equipment and process parameters. Equipment model: CM-MTE75 twin-screw extruder (Hongyu Machinery); Temperature gradient control: Feeding section: 170 - 180 °C (to prevent premature decomposition of DCP), mixing section: 190 - 200 °C (to achieve melt blending), die head section: 180 - 190 °C (to ensure uniformity of the rubber compound), Screw speed: 200 - 250 rpm (to balance dispersion and shear), Mixing time: 6 - 7 min (to optimize dispersion efficiency). Key points: Polyester fiber needs to be pre-dried (105 °C × 2 h, moisture content ≤ 0.5%), Iron-doped nano-aluminum oxide is fed in segments (70% is added at the main feeding port, 30% is added at the side feeding port). Dynamic vulcanization stage: Equipment and process parameters. Equipment model: XM-270 internal mixer (Dalian Rubber & Plastics Machinery), Vulcanization parameters: Temperature: 200 - 210 °C (nitrogen protection, oxygen content < 100 ppm), Pressure: 10 - 12 MPa (pressurized in three stages: 0 → 5 → 10 MPa), Shear rate: 1000 - 1200 s⁻¹ (rotor speed 40 - 45 rpm), Time: 12 - 13 min (including 1 min for exhaust); Crosslinking agent addition: Added in two times: 70% is added initially, 30% is added in the middle, and a loss-in-weight feeder is used (accuracy ±0.5%). Gradient pressing stage: Equipment and process parameters. Press model: YTD32-500 four-column hydraulic press (Nantong Forging). First-stage pressing: Temperature: 180 ± 2 °C (infrared temperature measurement on the die surface), Pressure: 15 MPa (holding pressure time 5 min), Function: To form a dense surface layer with a high grafting rate (15%). Second-stage pressing: Temperature: 220 ± 2 °C (monitored by internal thermocouple), Pressure: 20 MPa (holding pressure time 8 min), Function: To regulate the grafting rate (5%) of the core layer to form a gradient, Cooling method: Composite cooling of water cooling + air cooling (cooling rate 50 °C / min), Demolding temperature ≤ 60 °C (to prevent thermal deformation). Post-treatment stage: Surface treatment process, Grinding equipment: MK2150 CNC grinding machine (Hangzhou Machine Tool), Process parameters: Grinding wheel grit: 120# → 240# → 400# three-stage grinding, Feed speed: 2 - 3 m / min, Coolant: Water-based emulsion (flow rate 10 L / min); Quality control: Roughness: Ra1.2 - 1.5 μm (detected by white light interferometer), Dimension tolerance: ±0.1 mm (measured by coordinate measuring machine).

[0021] Application of the anti-high-temperature solid tire tread material as described above in the preparation of solid tires.

[0022] In summary, the beneficial effects of the present invention are as follows: Excellent high-temperature stability: By using iron-doped alumina with a nanoporous structure and a composite cross-linking system, the molecular chain slip and thermal aging phenomenon of the material under high-temperature conditions are effectively inhibited, thereby significantly improving the stability and durability of the tread material under continuous high-temperature and heavy-load conditions. Enhanced mechanical properties: The composite system formed by the matrix resin and the maleic anhydride graft copolymer enhances the creep resistance and crack resistance of the material through chemical bonding and molecular chain entanglement; at the same time, the addition of recycled polyester fibers improves the interfacial bonding and mechanical interlocking effects, overall enhancing the tensile strength, tear strength, and wear resistance. Gradient structure optimization: Through the gradient pressing technology, a structure with a high grafting rate on the surface layer and a low grafting rate on the core layer is formed, achieving a stress buffering effect of hard outside and tough inside, making the material perform more balanced in terms of wear resistance and impact resistance, and extending the service life of the tire. Environmental protection and resource utilization: Using polyester fibers recycled from waste tires as recycled materials not only reduces the raw material cost but also realizes the reuse of resources, meeting the current requirements of environmental protection and sustainable development. Significantly improved comprehensive performance: The synergistic effect of the dynamic vulcanization and static cross-linking processes optimizes the cross-linking network structure, enabling the overall material to maintain excellent performance under high-temperature, heavy-load, and complex working conditions, with the service life extended by 2-3 times, fully meeting the demanding requirements of special application fields such as port machinery and mining equipment.

[0023] Therefore, the present invention not only significantly improves the heat resistance and mechanical properties of the solid tire tread under high-temperature and heavy-load conditions, but also effectively reduces the production cost and environmental burden by using environmentally friendly recycled materials, and has broad industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a scanning electron micrograph of the tread material prepared in Example 8.

[0025] Figure 2 It is a real picture of the tread material prepared in Example 8. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The present invention will be described in detail below through specific embodiments, but the uses and purposes of these exemplary embodiments are only used to illustrate the present invention, and do not constitute any form of limitation on the actual protection scope of the present invention, nor will the protection scope of the present invention be limited thereto. At the same time, for the parameter ranges not mentioned in the examples or comparative examples, the intermediate value or the lowest value or the highest value of the parameter range is selected.

[0027] Design the following experimental system (total reference weight 100 grams).

[0028] Example 1

[0029] Matrix resin: 30 g of ethylene-propylene copolymer + 10 g of maleic anhydride graft copolymer (3:1, grafting rate 5%); Reinforcing filler: 2 g of iron-doped Al2O3 (Fe / Al2O3 = 1:8, specific surface area 250 m² / g); Recycled material: 2 g of polyester fiber (diameter 10 μm, aspect ratio 50); Crosslinking system: 0.5 g of DCP + 1.5 g of BMI (1:3).

[0030] Preparation process: Dynamic vulcanization: 190 °C / 10 MPa / 12 min, shear rate 1000 s⁻¹; Gradient pressing: 180 °C / 15 MPa / 5 min → 220 °C / 20 MPa / 8 min; Plasma treatment: 100 W / 4 min.

[0031] Example 2

[0032] Matrix resin: 32 g of ethylene-propylene copolymer + 8 g of graft copolymer (4:1, grafting rate 12%); Reinforcing filler: 4 g of iron-doped Al2O3 (Fe / Al2O3 = 1:9, specific surface area 300 m² / g); Recycled material: 4 g of polyester fiber (diameter 30 μm, aspect ratio 100); Crosslinking system: 0.6 g of DCP + 2.4 g of BMI (1:4).

[0033] Preparation process: Dynamic vulcanization: 200 °C / 12 MPa / 14 min, shear rate 1200 s⁻¹, Gradient pressing: 185 °C / 16 MPa / 6 min → 225 °C / 22 MPa / 9 min.

[0034] Example 3

[0035] Matrix resin: 35 g of ethylene-propylene copolymer + 7 g of graft copolymer (5:1, grafting rate 10%); Reinforcing filler: 6 g of iron-doped Al2O3 (Fe / Al2O3 = 1:10, specific surface area 350 m² / g); Recycled material: 5 g of polyester fiber (diameter 50 μm, aspect ratio 200); Crosslinking system: 0.8 g of DCP + 3.2 g of BMI (1:4).

[0036] Preparation process: Dynamic vulcanization: 210 °C / 11 MPa / 13 min, shear rate 1100 s⁻¹; Plasma treatment: 120 W / 5 min.

[0037] Example 4

[0038] Matrix resin: 34 g of ethylene-propylene copolymer + 6 g of graft copolymer (5.7:1, grafting rate 8%); Reinforcing filler: 3 g of iron-doped Al2O3 (Fe / Al2O3 = 1:8.5); Recycled material: 3 g of polyester fiber (diameter 20 μm, aspect ratio 80); Crosslinking system: 0.7 g of DCP + 2.1 g of BMI (1:3).

[0039] Preparation process: Gradient pressing: 182 °C / 15.5 MPa / 5.5 min → 218 °C / 21 MPa / 8.5 min.

[0040] The parameter combinations of Examples 5 - 10 are shown in Table 1 below:

[0041] Table 1

[0042]

[0043] Comparative Example 1

[0044] Matrix resin: 40 g of pure ethylene - propylene copolymer; other components are the same as in Example 1.

[0045] Comparative Example 2

[0046] Reinforcing filler: 2 g of undoped Al2O3; others are the same as in Example 1.

[0047] Comparative Example 3

[0048] Crosslinking system: 1.2 g of DCP + 0.8 g of BMI (1:0.67).

[0049] Comparative Example 4

[0050] Preparation process: Single - stage pressing at 200 °C / 20 MPa / 13 min.

[0051] Comparative Example 5

[0052] Preparation of Al2O3: Calcination temperature 500 °C.

[0053] Comparative Example 6

[0054] Preparation of crosslinking agent: Omit the plasma treatment step.

[0055] Comparative Example 7

[0056] Polyester fiber: 8 g (exceeding the upper limit).

[0057] Comparative Example 8

[0058] Al2O3: Conventional spherical nanoparticles.

[0059] The test plan is as follows: Mechanical property test: Tensile strength: ASTM D412, dumbbell-shaped specimen, tensile rate 500 mm / min; Tear strength: ASTM D624, right-angle tear specimen, test temperature 150 °C; Hardness: ASTM D2240, Shore A durometer, equilibrated for 24 h at 23 °C. Dynamic thermomechanical analysis (DMA): Equipment: TA Q800 dynamic thermomechanical analyzer, Conditions: temperature range -50~200 °C, heating rate 3 °C / min, frequency 1 Hz, Parameters: storage modulus (E'), loss factor (tanδ). Abrasion resistance: Akron abrasion: GB / T 1689, load 26.7 N, abrasion distance 1.61 km, DIN abrasion: DIN 53516, test temperature 100 °C. Thermal aging test: Conditions: 150 °C air-circulating oven, 72 h aging, Performance retention rate: Tensile strength retention rate = (strength after aging / original strength) × 100%.

[0060] Table 1 Comparison of basic mechanical properties (test temperature 23 °C)

[0061]

[0062] Table 2 High-temperature performance test (150 °C)

[0063]

[0064] Table 3 Performance changes after thermal aging (150 °C / 72 h)

[0065]

[0066] By comparing the performance data of the examples and the comparative examples (Tables 1-3), the performance optimization mechanism and key influencing factors of the high-temperature resistant solid tire tread material are revealed. Influence of the matrix resin system on mechanical properties: Grafting ratio and proportion regulation: When the ratio of ethylene-propylene copolymer to graft copolymer is 4.2:1 (Example 6), the tensile strength reaches 30.5 MPa, which is 58.9% higher than that of the pure matrix (Comparative Example 1). The increase in the content of polar groups improves the filler dispersion through hydrogen bonding, but when the grafting ratio exceeds 14% (Example 6), the molecular chain rigidity becomes too strong and the toughness decreases. Gradient structure effect: The 15%-5% grafting ratio gradient formed by two-stage pressing (Example 8) enables the modulus retention rate of the material to reach 96% at 150 °C, which is 43.3% higher than that of single-stage pressing (Comparative Example 4). The high grafting ratio (15%) on the surface inhibits thermal softening, and the low grafting ratio (5%) in the core layer maintains elasticity. Mechanism of action of reinforcing fillers: Iron-doped porous Al2O3: In Example 2 containing 1:9 Fe / Al2O3, its high-temperature tensile strength (27.3 MPa) is 88.3% higher than that of the undoped Comparative Example 2. Iron elements generate oxygen vacancies through lattice distortion, enhancing the π-π interaction with the resin. DMA shows that its tanδ peak temperature reaches 162 °C, which is 34 °C higher than that of conventional Al2O3 (Comparative Example 8). Optimization of pore structure: The filler with a specific surface area of 300 m² / g (Example 2) reduces the Akron abrasion to 0.12 cm³, which is 68.4% lower than that of Comparative Example 5 with a pore volume of 0.4 cm³ / g. The porous structure locks the pyrolysis products through physical adsorption, delaying the oxidation chain reaction. Dynamic vulcanization process: A shear rate of 1200 s⁻¹ (Example 8) improves the orientation degree of the crosslinking network, and the tensile strength at 150 °C reaches 28 MPa, which is 36.6% higher than that of the static vulcanization process (Comparative Example 6). High shear promotes the alignment of crosslinking agents along the stress direction, forming an anisotropic network. Plasma treatment: The crosslinking agent treated with 120 W plasma (Example 3) increases the hardness retention rate of the material by 9% (Table 3). The surface active groups (-COOH content increases by 15%) promote covalent bonding with the resin, and XPS shows that the proportion of C=O bonds increases from 12% to 18%. Reinforcement mechanism of recycled materials: The polyester fiber (diameter 30 μm, aspect ratio 100) in Example 2 enables the tear strength to reach 70.8 kN / m, which is 87.3% higher than that of Comparative Example 7 without fibers. The microcracks on the fiber surface hinder crack propagation through the "pinning effect", and SEM shows that the fracture surface presents a typical fiber pull-out morphology. High-temperature performance and aging behavior: Thermal stability: The optimal Example 8 has a tensile retention rate of 93% after aging at 150 °C for 72 h, which is 50% higher than that of the filler-free matrix system (Comparative Example 2). Iron ions inhibit free radical generation through the Fenton reaction, and FTIR shows that the C-H bond breakage rate decreases by 62%. Dynamic mechanical response: The tanδ peak temperature is positively correlated with the glass transition temperature. The 163 °C peak of Example 8 indicates that its upper limit of effective use temperature is 31 °C higher than that of traditional materials (Comparative Example 1).The storage modulus E' still remains at 1.2 GPa at 100 °C, meeting the requirements for heavy loads. Through the above mechanism analysis, it can be seen that the improvement of material properties stems from the multi-scale synergistic effect: nano-fillers improve thermal stability, the gradient structure optimizes stress distribution, and dynamic crosslinking enhances network strength. This system provides a theoretical basis and process guidance for the development of high-temperature heavy-duty tires.

[0067] Example 8 achieves the best balance among the following key indicators: Strength-toughness balance: The elongation at break is maintained at 380% with a grafting rate of 11%, which is better than that of Example 6 with a high grafting rate (14%, 280%). Wear-resistance-impact resistance balance: The surface hardness of 86 Shore A forms a gradient buffer with the core layer impact strength (23 kJ / m²). Cost-performance ratio: Compared with 3 g (Example 4) and 5 g (Example 3) of the recycled fiber content, the raw material cost is reduced by 15% while maintaining the performance. Example 8 demonstrates comprehensive advantages in the following three aspects: Adaptability to extreme working conditions: It still maintains 93% of the tensile strength after continuous aging at 150 °C for 72 h, meeting the requirements of 18 h of continuous operation per day for port machinery. Economic benefits: The service life reaches 3 times that of traditional materials, and the average annual maintenance cost per tire is reduced by 67%. Process stability: The tolerance range of key parameters is wider (for example, the grafting rate allows a fluctuation of ±2%), which is more suitable for large-scale production. At the same time, the micro scanning electron microscope image of the prepared tire tread material is as Figure 1 shown, and the prepared tread material is as Figure 2 shown.

[0068] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present invention, and they are not intended to limit the protection scope of the present invention. Any equivalent embodiments or changes made without departing from the technical spirit of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-temperature resistant solid tire tread material, characterized in that, It comprises the following components: a) Matrix resin: a composite system composed of ethylene-propylene copolymer and maleic anhydride-grafted ethylene-propylene copolymer, wherein the grafting rate of the maleic anhydride-grafted ethylene-propylene copolymer is 5-15 wt%, and the weight ratio of the ethylene-propylene copolymer to the maleic anhydride-grafted ethylene-propylene copolymer is 3:1 to 5:1, with a content of 30-40 parts by weight; b) Reinforcing filler: iron-doped porous nano-alumina particles, wherein the mass ratio of Fe to Al2O3 is 1:8 to 1:10, with a content of 2-8 parts by weight; c) Recycled material: polyester fiber obtained by recycling waste tires, with a content of 2-6 parts by weight; d) Crosslinking system: a composite crosslinking agent composed of dicumyl peroxide and m-phenylenediamine-based bismaleimide, with a content of 2-4 parts by weight.

2. The high-temperature resistant solid tire tread material according to claim 1, wherein The described iron-doped porous nano-aluminum oxide particles are prepared by the following method: Mix aluminum nitrate and iron nitrate in a mass ratio of 8:1 - 10:1, and calcine at 550 - 650 °C for 2 - 4 h to form a porous structure with a pore diameter of 40 - 50 nm and a pore volume of 0.5 - 0.6 cm 3 / g, and the specific surface area is ≥ 250 m 2 / g.

3. The anti-high temperature solid tire tread material according to claim 1, characterized in that, The CAS number of the ethylene-propylene copolymer is 9010-79-1; the CAS number of the maleic anhydride-grafted ethylene-propylene copolymer is 31069-12-2.

4. The high-temperature resistant solid tire tread material according to claim 1, characterized in that, The diameter of the polyester fiber is 10-50 μm, and the aspect ratio is 50-200.

5. The anti-high-temperature solid tire tread material according to claim 1, characterized in that, The mass ratio between the dicumyl peroxide and the m-phenylenediamine-based bismaleimide is 1:3 to 1:

5.

6. The high-temperature resistant solid tire tread material according to claim 2, characterized in that, The specific surface area of the iron-doped porous nano-alumina particles described is 250-350 m 2 / g, and the most probable pore diameter is 40-50 nm.

7. The high-temperature resistant solid tire tread material according to claim 1, characterized in that, The preparation method of the composite crosslinking agent is as follows: Mix dicumyl peroxide and m-phenylenediamine-based bismaleimide, add them to a high-speed mixer, and premix at 25-35 °C and a rotation speed of 500-800 rpm for 10-15 min; Transfer the premix to a twin-screw extruder, set the temperature gradient as 80-100 °C for the feeding section, 150-180 °C for the kneading section, 120-140 °C for the head section, the screw rotation speed of 200-300 rpm, and extrude and pelletize; Place the pellets in a plasma treatment device, and treat them under an argon atmosphere at a pressure of 50-100 Pa and a power of 80-120 W for 3-5 min, and classify them through a 20-40 mesh sieve to obtain composite crosslinking agent particles with uniform particle size.

8. The high-temperature resistant solid tire tread material according to claim 1, characterized in that, The preparation method of the high-temperature resistant solid tire tread material is as follows: Matrix mixing: Add ethylene-propylene copolymer, maleic anhydride grafted ethylene-propylene copolymer, polyester fiber and iron-doped porous nano-aluminum oxide particles into a twin-screw extruder, set the temperature gradient at 170-200 °C, the screw speed at 150-300 rpm, and the mixing time at 5-8 min to obtain a uniform premix; Dynamic vulcanization: Transfer the premix to an internal mixer, add a composite cross-linking agent, and vulcanize at 180-220 °C and a pressure of 8-12 MPa for 10-15 min, and control the shear rate at 800-1200 s -1 ; Gradient pressing: Place the vulcanized rubber compound in a mold and press it in two stages: The first stage: temperature 180 °C, pressure 15 MPa, time 5 min; The second stage: temperature 220 °C, pressure 20 MPa, time 8 min to form a gradient structure with a surface grafting rate of 15% and a core grafting rate of 5%; Post-treatment: After cooling to room temperature, polish the surface to make the roughness Ra ≤ 1.6 μm to obtain the final tread material.

9. Use of the high-temperature-resistant solid tire tread material according to any one of claims 1-8 in the preparation of solid tires.

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